Despite the inherent structural complexity of glycans and the greater difficulty in defining their sequences and the fact that their biosynthesis could not be directly predicted from a DNA template, it is now well recognized that glycans are irreplaceable parts of all organisms critical to the development, cellular functions and sustaining the very existence of life forms in the surrounding matrix. Such processes are typically linked to not just monosaccharide units, but to oligosaccharides and their glycoconjugates as well. Therefore, studying the synthesis of oligossacharides will allow us to understand the relationship between their functionalities and the biological activities that they mediate. Protective group strategies are an important part of the synthesis as they are used for the manipulations of the structures. In 2021, the Department of Pharmaceutical Chemistry at the University of Debrecen carried out a study on reductive ring opening reactions of halobenzylidene acetals using reagent combinations commonly employed in benzylidene-type acetals. Halobenzylidene type acetals and their reductive openings offer an excellent method for the regioselective introduction of versatile halobenzyl protecting groups. This thesis work continues the similar study on halobenzylidene diacetals on a mannopyranoside derivative.